Subject:
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Re: Quad intersections
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Newsgroups:
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lugnet.cad.dev
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Date:
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Fri, 16 Apr 1999 18:37:22 GMT
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Viewed:
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654 times
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On Fri, 16 Apr 1999 17:35:09 GMT, "John VanZwieten"
<john_vanzwieten@email.msn.com> wrote:
> Based on Dave's formulae, I have been able to calculate the intersection of a
> plane (given three points) and a line (given two points). How do I then
> determine whether the point of intersection falls within a quad (as in Dave's
> "exercise left for the reader")?
Using quad points Q0 - Q3, point of intersection I.
For all lines QmQn, where I.X is between Qm.X and Qn.X, interpolate the
point Jmn on QmQn where Jmn.X = I.X.
If I.Z is between min(Jmn.Z) and max(Jmn.Z) then I lies within quad Q. If
I.Z is equal to either min(Jmn.Z) or max(Jmn.Z), then I is on the edge of
the quad.
This is assuming that Q does not lie in a vertical plane.
There's probably a more elegant solution, but this one works.
Steve
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Message is in Reply To:
 | | Re: Quad intersections
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| Based on Dave's formulae, I have been able to calculate the intersection of a plane (given three points) and a line (given two points). How do I then determine whether the point of intersection falls within a quad (as in Dave's "exercise left for (...) (25 years ago, 16-Apr-99, to lugnet.cad.dev)
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